Arch Rib Analysis

[rkhan01]

Can someone please help me with this problem I am currently experiencing. Right, I am carrying out an analysis (detailed calculation) on an arch rib from a tied arch bridge spanning 24m. The length of the arch is 26m with a rise of 4m. The arch consists of a steel circular hollow section with a diameter of 244.5mm and 10mm thickness (I have all the material properties listed i.e. mass, moment of inertia, elastic modulus etc.). The arch is tied to the main tie by means of welding which means this is a FIXED support. I now have a statically indeterminate structure (correct me if i'm wrong). This is the trouble I am having as I am unsure how to calculate the vertical, horizontal and moment forces of the arch. I have looked everywhere online and books but still cannot seem to figure it out to my specific scenario.
SOMEONE PLEASE HELP!!

Much Appreciated

 

[GWWilliam]

I have done this type of analysis many years ago. Do you have ties or struts? How many are they in the 26 m span? what is their cross-section? The cross section of the ties should be relatively small compared to the arch rib. So, you may assume that they hinged despite the fact they are welded for the preliminary analysis, or you can take the problem to an FE software.
The arch rib is treated as either hinged-hinged or fixed-fixed, so it is externally statically indeterminate anyway? If you want to do hand calculations, you can find values for straining action forces in a typical structural engineering handbook, especially old ones. I used to have couple of those. I hope this would help.